Radio frequency splitter
A multichannel splitter formed from 1 to 2 splitters. An input terminal of a first 1 to 2 splitter defines an input of the multichannel splitter. The 1 to 2 splitters are electrically series-connected. First respective outputs of the 1 to 2 splitters define output terminals of the multichannel splitter.
1. A radio frequency transmission system comprising:
a transceiver circuit capable of receiving baseband signals and of providing a signal to be transmitted;
a first 1-to-2 splitter that includes an input terminal coupled to the transceiver circuit to receive the signal to be transmitted and a first output that is to be coupled to a first channel;
a second 1-to-2 splitter that includes an input terminal coupled to a second output of the first 1-to-2 splitter and a first output that is to be coupled to a second channel; and
a third 1-to-2 splitter that includes an input terminal coupled to a second output of the second 1-to-2 splitter and a first output that is to be coupled to a third channel.
2. The system of claim 1 , wherein each channel further comprises a 2-to-1 combiner, the combiners of different channels being electrically series-connected.
3. The system of claim 1 , further comprising a plurality of 2-to-1 combiners, wherein:
an output terminal of a first 2-to-1 combiner is coupled to receive input of the transceiver;
an output terminal of a second 2-to-1 combiner is coupled to a first input of the first 2-to-1 combiner; and
an output terminal of a third 2-to-1 combiner is coupled to a first input of the second 2-to-1 combiner.
4. The system of claim 3 , wherein:
a second input of the first 2-to-1 combiner is coupled to the first channel;
a second input of the second 2-to-1 combiner is coupled to the second channel; and
a second input of the third 2-to-1 combiner is coupled to the third channel.
5. The system of claim 1 , further comprising:
a first antenna coupled to the first channel;
a second antenna coupled to the first channel; and
a third antenna coupled to the first channel, wherein the first, second and third antennas form an antenna array.
6. The system of claim 5 , further comprising:
a first amplifier coupled in the first channel between the first 1-to-2 splitter and the first antenna;
a second amplifier coupled in the second channel between the second 1-to-2 splitter and the second antenna; and
a third amplifier coupled in the third channel between the third 1-to-2 splitter and the third antenna.
7. The system of claim 1 , further comprising a digital-to-analog circuit coupled between the input terminal of the first 1-to-2 splitter and the transceiver circuit.
8. The system of claim 7 , further comprising a modulator coupled between the digital-to-analog circuit and the input terminal of the first 1-to-2 splitter.
9. The system of claim 1 , wherein the first, second and third 1-to-2 splitters each comprise:
a first λ/4 line having a first end and a second end;
a second λ/4 line having a first end and a second end, wherein the first end of the first λ/4 line and the first end of the second λ/4 line are connected together and form an input of the 1-to-2 splitter; and
an impedance connected between the second end of the first λ/4 line and the second end of the second λ/4 line, wherein the second end of the first λ/4 line forms a first output of the 1-to-2 splitter and wherein the second end of the second λ/4 line forms a second output of the 1-to-2 splitter.
10. The system of claim 1 , further comprising:
a first 2-to-1 combiner that includes an output terminal coupled to a receive input of the transceiver circuit and a first input coupled to a first channel;
a second 2-to-1 combiner that includes an output terminal coupled to a second input of the first 2-to-1 combiner and a first input coupled to a second channel; and
a third 2-to-1 combiner that includes an output terminal coupled to a second input of the second 2-to-1 combiner and a first input coupled to a third channel.
11. The system of claim 10 , further comprising:
a first antenna coupled to the first channel;
a second antenna coupled to the first channel; and
a third antenna coupled to the first channel, wherein the first, second and third antennas form an antenna array.
12. The system of claim 11 , further comprising:
a first amplifier coupled in the first channel between the first 2-to-1 combiner and the first antenna;
a second amplifier coupled in the second channel between the second 2-to-1 combiner and the second antenna; and
a third amplifier coupled in the third channel between the third 2-to-1 combiner and the third antenna.
13. The system of claim 10 , further comprising a digital-to-analog circuit coupled between the output terminal of the first 2-to-1 combiner and the transceiver circuit.
14. The system of claim 13 , further comprising a modulator coupled between the digital-to-analog circuit and the output terminal of the first 2-to-1 combiner.
15. A method comprising:
(a) receiving an original signal for transmission;
(b) splitting the signal into two sub-signals;
(c) passing a first of the two sub-signals to a first antenna;
(d) splitting a second of the two sub-signals into two further sub-signals;
(e) passing a first of the two further sub-signals to an (N i )th antenna;
(f) splitting a second of the two further sub-signals into two next sub-signals;
(g) repeating steps (e) and (f) until (N−1) sub-signals having been passed to N−1 antennas; and
(h) passing a last of the sub-signals to an Nth antenna, where N is an integer, and where i varies from 1 to N such that each sub-signal is passed to a respective one antenna.
16. The method of claim 15 further comprising:
(i) receiving N original sub-signals;
(j) combining a sub-signal N 1 with a sub-signal N 2 to form a combined signal C j ;
(k) combining a sub-signal N i with combined signal C j ; and
(l) repeating step (j) until all N sub-signals have been combined as i varies from 3 to N and as j varies from 1 to N−1.
17. The method of claim 16 wherein N equals 3.
18. The method of claim 15 , wherein:
step (b) is performed by a first 1-to-2 splitter;
step (c) comprises passing the first of the two sub-signals from a first output of the first 1-to-2 splitter to the first antenna; and
step (d) comprises passing the second of the two sub-signals from a second output of the first 1-to-2 splitter to a second 1-to-2 splitter.
19. The method of claim 18 , wherein:
step (e) comprises passing the first of the two further sub-signals from a first output of the second 1-to-2 splitter to the (N i )th antenna; and
step (f) comprises passing the second of the two further sub-signals to a (N i )th splitter.
20. The method of claim 15 , wherein the method is performed using a multichannel splitter that includes an input and a plurality of outputs, wherein the multichannel splitter comprises:
a first 1-to-2 splitter that includes an input terminal that receives the original signal for transmission and a first output that serves to pass the first of the two sub-signals to the first antenna;
a second 1-to-2 splitter that includes an input terminal coupled to a second output of the first 1-to-2 splitter, wherein the second 1-to-2 splitter splits the second the second of the two sub-signals into the two further sub-signals; and
a third 1-to-2 splitter that includes an input terminal coupled to a second output of the second 1-to-2 splitter.
21. The method of claim 20 , wherein the a multichannel splitter further comprises a fourth 1-to-2 splitter that includes an input terminal coupled to a second output of the third 1-to-2 splitter.
22. The method of claim 20 , further comprising:
amplifying the first of the two sub-signals; and
amplifying the first of the two further sub-signals.
23. The method of claim 22 , wherein the first of the two sub-signals is amplified using a first fixed gain amplifier with a gain of about 3 dB and the first of the two further sub-signals a second fixed gain amplifier with a gain of about 3 dB.
24. A radio frequency transmission system comprising:
a transceiver circuit capable of receiving baseband signals and of providing a signal to be transmitted;
a first 1-to-2 splitter that includes an input terminal coupled to the transceiver circuit to receive the signal to be transmitted and a first output that is to be coupled to a first channel;
a second 1-to-2 splitter that includes an input terminal coupled to a second output of the first 1-to-2 splitter and a first output that is to be coupled to a second channel;
a third 1-to-2 splitter that includes an input terminal coupled to a second output of the second 1-to-2 splitter and a first output that is to be coupled to a third channel; and
a digital-to-analog circuit coupled between the input terminal of the first 1-to-2 splitter and the transceiver circuit;
wherein the first, second and third 1-to-2 splitters each comprise:
a first λ/4 line having a first end and a second end;
a second λ/4 line having a first end and a second end, wherein the first end of the first λ/4 line and the first end of the second λ/4 line are connected together and form an input of the 1-to-2 splitter; and
an impedance connected between the second end of the first λ/4 line and the second end of the second λ/4 line, wherein the second end of the first λ/4 line forms a first output of the 1-to-2 splitter and wherein the second end of the second λ/4 line forms a second output of the 1-to-2 splitter.
25. The system of claim 24 , wherein each channel further comprises a 2-to-1 combiner, the combiners of different channels being electrically series-connected.
26. The system of claim 24 , further comprising a plurality of 2-to-1 combiners, wherein:
an output terminal of a first 2-to-1 combiner is coupled to receive input of the transceiver;
an output terminal of a second 2-to-1 combiner is coupled to a first input of the first 2-to-1 combiner; and
an output terminal of a third 2-to-1 combiner is coupled to a first input of the second 2-to-1 combiner.
27. The system of claim 26 , wherein:
a second input of the first 2-to-1 combiner is coupled to the first channel;
a second input of the second 2-to-1 combiner is coupled to the second channel; and
a second input of the third 2-to-1 combiner is coupled to the third channel.
28. The system of claim 24 , further comprising:
a first antenna coupled to the first channel;
a second antenna coupled to the first channel; and
a third antenna coupled to the first channel, wherein the first, second and third antennas form an antenna array.
29. The system of claim 28 , further comprising:
a first amplifier coupled in the first channel between the first 1-to-2 splitter and the first antenna;
a second amplifier coupled in the second channel between the second 1-to-2 splitter and the second antenna; and
a third amplifier coupled in the third channel between the third 1-to-2 splitter and the third antenna.
30. The system of claim 24 , further comprising a modulator coupled between the digital-to-analog circuit and the input terminal of the first 1-to-2 splitter.